This invention relates to a retrieval system for executing a data search processing.
JP 63-80325 A relates to an information retrieval method and an index, describing a technology in which a keyword included in search criteria preregistered by an operator and a keyword included in the index are compared with each other according to a predetermined logical conditional expression at a reserved search execution time preregistered by the operator, and update data having a keyword that satisfies the predetermined Boolean expression is retrieved, the update data having been updated after a previous search using the same search criteria as the current search.
In JP 63-80325 A, there is provided an index registered with a keyword and data update time regarding update data. When the data is updated, the update data is associated with the keyword and the data update time within the index. When the search is executed, the index is referenced to obtain the update data updated within a period specified for the search.